# NTSB GAA17CA436: Bell 47G 3B, N47AH, Toterville, IA, July 24, 2017 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: July 24, 2017, 16:00 local (21:00 UTC) - Place: Toterville, IA - Coordinates: 43.438888, -92.782218 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=43.4389&lon=-92.7822&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Loss of control in flight](https://openairdocs.org/ntsb-events/240) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report April 23, 2018 - Report: Approved by Office Director - NTSB office: General Aviation Accidents - Parties: FAA - NTSB case key (mKey): 95655 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=GAA17CA436 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/95655/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=95655 - Page: https://openairdocs.org/ntsb/GAA17CA436 ## Probable cause The pilot’s failure to maintain rotor rpm while maneuvering at low altitude with low airspeed and a tailwind. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Bell 47G-3B, 5 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=1181026), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Wind: tailwind](https://openairdocs.org/ntsb-findings/03034015): Environmental issues › Conditions/weather/phenomena · Effect on operation (probable cause); cases with it: [Bell 47G-3B, 1 case](https://openairdocs.org/ntsb-findings/03034015/cases.md?model=1181026), [All aircraft, 594 cases](https://openairdocs.org/ntsb-findings/03034015/cases.md) - [Performance/control parameters: prop/rotor parameters](https://openairdocs.org/ntsb-findings/01062052): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Bell 47G-3B, 2 cases](https://openairdocs.org/ntsb-findings/01062052/cases.md?model=1181026), [All aircraft, 182 cases](https://openairdocs.org/ntsb-findings/01062052/cases.md) - [Performance/control parameters: airspeed](https://openairdocs.org/ntsb-findings/01062010): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Bell 47G-3B, 1 case](https://openairdocs.org/ntsb-findings/01062010/cases.md?model=1181026), [All aircraft, 1,681 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md) - [Performance/control parameters: altitude](https://openairdocs.org/ntsb-findings/01062012): Aircraft › Aircraft oper/perf/capability · Attain/maintain not possible (probable cause); cases with it: [Bell 47G-3B, 1 case](https://openairdocs.org/ntsb-findings/01062012/cases.md?model=1181026), [All aircraft, 1,310 cases](https://openairdocs.org/ntsb-findings/01062012/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-low-alt flying: Loss of control in flight](https://openairdocs.org/ntsb-events/240) (defining event); cases with it: [Bell 47G-3B, 7 cases](https://openairdocs.org/ntsb-events/240/sequence.md?model=1181026), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) - [Maneuvering-low-alt flying: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Bell 47G-3B, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=1181026), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis According to the helicopter pilot, during an agricultural flight, he made a downwind turn to spray the intended field. During the low airspeed right turn, he increased the engine power, and the rotor rpm decreased. He reported that he leveled the helicopter to clear power lines, but the rotor rpm remained low. The helicopter descended, and the pilot landed the helicopter in a corn field. The helicopter sustained substantial damage to the tailboom and horizontal stabilizer. The nearest METAR located 15 nautical miles south-southeast from the accident site reported that, about the time of the accident, the wind was calm. The pilot reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation. ## Factual narrative According to the helicopter pilot, during an agricultural flight, he made a downwind turn to spray the intended field. During the low airspeed right turn, he increased the engine power and the rotor RPM decreased. He reported that he leveled the helicopter to clear powerline wires, but the rotor RPM remained low. The helicopter descended, and the pilot landed the helicopter in a corn field. The helicopter sustained substantial damage to the tailboom and the horizontal stabilizer. The nearest METAR was 15 nautical miles south-southeast and reported that about the time of the accident, the wind was calm. The pilot reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation. ## Aircraft - Registration: [N47AH](https://openairdocs.org/aircraft/N47AH), registered now, S/N 2645, built 1961 (OpenAirDocs) - Reported make and model: BELL 47G 3B (3B) - Registry model: [Bell 47G-3B](https://openairdocs.org/model/bell-47g-3b) (registry code 1181026) (OpenAirDocs) - Registry engine: [Lycoming TVO-435-GIA](https://openairdocs.org/engine/lycoming-tvo-435-gia) (registry code 41526, turbo-prop) (OpenAirDocs) - Category: Helicopter - Serial number: 2645 - Year built: 1961 - Airframe hours: 14259 - Engines: LYCOMING TV0-435 SER 250 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Scotts Helicopter Service Inc - Registered owner: Scotts Helicopter Service Inc - Airworthiness certificate: Special, Restricted (Special); Standard, Normal - Last inspection: Annual, May 1, 2017 - Departed: Toterville, IA - Destination: Toterville, IA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 33; injuries: none; private; airplane ratings: single-engine land; medical: class 2, without waivers/limitations; last flight review April 13, 2017; seat: left; restraint: 4-point; flight hours: 389 total, 1 in this make and model, 150 in the last 90 days, 100 in the last 30 days, 10 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 7 statute miles - Lowest ceiling: none - Temperature: 57 °F, dew point 55 °F - Altimeter: 30.03 inHg - Observed at: KAUM, 15 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20170724020609A](https://openairdocs.org/incident/20170724020609A), Jul 24, 2017: Bell 47G-3B, Toeterville, IA, Substantial damage. While performing agricultural spray operations five miles west of stacyville, IA. The pilot failed to maintain sufficient rotor prm to arrest his descent from… ## Other investigations on N47AH (2) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB CHI08CA254](https://openairdocs.org/ntsb/CHI08CA254), Aug 14, 2008: Bell 47G-3B (N47AH), Kenyon, MN, substantial damage. Probable cause: The pilot's inadequate preflight planning which resulted in the helicopter settling with power. - [NTSB SEA98LA006](https://openairdocs.org/ntsb/SEA98LA006), Oct 19, 1997: Bell 47-G3B (N47AH), Winston, MT, substantial damage. Probable cause: Fuel starvation due to fuel flow restriction from a failed carburetor automatic mixture control device. Factors include night light conditions for the forced landing. ## Docket (2 files) The files NTSB released with the investigation on October 21, 2020, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=95655. 3.7 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 3.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=5740178&FileExtension=pdf&FileName=6120_1_Redacted-Rel.pdf - Photo (item 2, PDF, 1 page, 154 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=5739840&FileExtension=pdf&FileName=Photo-Rel.pdf From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.